Glacigenic rafting at Castle Hill,Gardenstown, and its significance for the glacial history of northern Banffshire,Scotland

Reinvestigation of the lower part of the key Quaternary section at Castle Hill, Gardenstown, has shown that the sediments are not in stratigraphical order, but consist chiefly of glaciotectonites, including rafts of soft sediments, which were deposited by ice moving southeastwards from the Moray Firth. Sedimentary structures are preserved in some of the rafts, which are separated by subhorizontal shears. The rafts accreted subglacially under conditions of moderate to high strain, the final glacial event being the deposition of a thin, discontinuous sheet of till, probably derived from a more westerly direction. It is proposed that interbedded dark grey shelly clay, till and sand elsewhere in northern Banffshire were emplaced, at least in part, by a similar mechanism during either the Middle Devensian, or more likely, the Late Devensian. Sand and clay with paired bivalve shells, which were formerly exposed within the Quaternary successions at Castle Hill and inland at King Edward, some 12 km to the south, are interpreted to be within glacigenic rafts, and are not in situ deposits formed during a widespread marine transgression. It is suggested that the alternation of phases of constructional and excavational deformation within a single glacial event rather than discrete glaciations provides a useful model for glacial deposition in northern Banffshire, and more generally in northeast Scotland. © 1997 John Wiley & Sons, Ltd.     

Interlobate ice-sheet dynamics during the Last Glacial Maximum at Whitburn Bay, County Durham, England

This research reconstructs ice-sheet processes operating during the Late Devensian in northeast England. The article assesses the lithostratigraphy of the Devensian glacial tills of Whitburn Bay, eastern County Durham, and presents the first detailed analysis of petrological, geochemical and biostratigraphical data to reconstruct lithostratigraphy, provenance and iceflow pathways. Two Devensian tractions tills (the Blackhall and Horden tills) are separated by a boulder pavement, pointing to a switch in ice-bed conditions and the production of a melt-out lag prior to deposition of the upper traction till, the Horden Till. The Blackhall Till contains Magnesian Limestone, Carboniferous Limestone, Whin Sill dolerite and Old Red Sandstone, suggesting a northwesterly source, probably from the Midland Valley and the Southern Uplands. The Horden Till contains erratics and heavy minerals derived from crystalline bedrock sources in the Cheviot Hills and northeast Scotland. Within the Horden Till are numerous sand, clay and gravel-filled canals incised downwards into the diamicton which are attributed to a low-energy, distributed, subglacial canal drainage system. Coupled with hydro-fractures and the boulder pavement, this suggests that a partially decoupled, fast-flowing ice stream deposited the Horden Till. The uphill, landward direction of ice movement indicates that the ice stream was confined in the North Sea Basin, possibly by the presence of Scandinavian Ice.     

Sedimentation and Iithostratigraphy of the North Sea Drift and Lowestoft Till Formations in the Coastal cliffs of northeast Norfolk,England

The most complete terrestrial sequence of Anglian (Elsterian) glacial sediments in western Europe was investigated in northeast Norfolk, England in order to reconstruct the evolution of the contemporary palaeoenvironments. Lithostratigraphically the glacial sediments in the northeast Norfolk coastal cliffs can be divided into the Northn Sea Drift and Lowestoft Till Formations. Three of the diamicton members of the North Sea Drift Formation (Happisburgh, Walcott and Cromer Diamictons) were deposited as lodgement and/or subglacial deformation till by grounded ice, but one, the Mundesley Diamicton, is waterlain and was deposited in an extensive glacial lake. Sands and fine sediments interbedded between the diamictons represent deltaic sands and glaciolacustrine sediments derived not solely from the melting ice in the north but also from extra-marginal rivers in the south. The Lowestoft Till Formation is not well preserved in the cliffs but includes lodgement till (Marly Drift till) and, most probably, associated meltwater deposits. Extensive glaciotectonism in the northern part of the area is shown to relate to oscillating ice that deposited the Cromer Diamicton and also partially to the ice sheet that deposited the Marly Drift till. It is suggested that during the Anglian Stage the present day northeast Norfolk coast was situated on the northwestern margin of an extensive glaciolacustrine basin. This basin was dammed by the Scandinavian ice sheet in the north and northeast. Because the grounding line of this ice sheet oscillated in space and time, part of the North Sea Drift diamictons were deposited directly by this ice. However, during ice retreat phases glaciolacustrine deposition comprised waterlain diamicton, sands and fines. When the Scandinavian ice sheet was situated in northernmost Norfolk, the British ice sheet (responsible for depositing the Marly Drift facies) entered the area from the west. This ice sheet partially deformed the North Sea Drift Formation sediments in the northern part of the area but not in the south, where the British ice sheet apparently terminated in water. The interplay of these two ice sheets on the northern and western margins of the glacial lake is thought to be the major determining factor for the accumulation of thick glacial deposits in this area during the Anglian glaciation.     

The Pre-Windermere Interstadial (Late Devensian) raised marine strata of eastern Scotland and their macrofauna: a review

Late Devensian raised marine deposits predating the Windermere Interstadial (c. 13–11 ka BP) are found between the Moray Firth and Berwick. The widely distributed, sparsely fossiliferous Errol Clay Formation of the firths of Forth and Tay was laid down in a high-arctic environment immediately following the retreat of the Late Devensian (Dimlington Stadial) ice. In the Tay Estuary, sedimentation took place under distal glaciomarine to marine conditions at a time when there was a fully marine connection between the Scottish east coast and the then high-arctic Norwegian Sea. On the south shore of the Moray Firth, the similar, but undated Spynie Clay Formation seems to have been laid down in a wholly glaciomarine environment. Part of the macrofauna attributed to the St. Fergus Silt Formation of the NE Scottish coast may have been either misidentified, or is not in situ. The preservation of the fauna and of delicate sedimentary structures indicate that the arctic clays as a whole were laid down rapidly. It is suggested that tidal currents were minimal, and that waves were dampened by sea ice for much of the year. Bones of the ringed seal, Phoca hispida, have been recorded from 12 sites in eastern Scotland. About 40 macrofaunal taxa are present in the Errol Clay Formation, a number similar to that recorded in the Danish Younger Yoldia Clay, which is of comparable age. The faunal nomenclature is updated, and three species (Cylichna occulta, Retusa obtusa and Lyonsia arenosa) are added to the macrofaunal list for the Errol Clay Formation. Reports of in situ boreal molluscs and of one possibly North American species in the otherwise high-arctic assemblage are not supported by specimens in extant collections. Differential decay of the fauna below the zone of weathering in the Errol Clay Formation may have resulted from early diagenesis. Deposition of the Late Devensian, pre-Windermere Interstadial marine sediments as a whole was probably diachronous, beginning after 15–14 ka BP on the outer coast, but was confined to a short interval (c. 13.5–13 ka BP) at the type site in the Tay Estuary. In the Forth Estuary, the high-arctic marine fauna adjacent to the retreating ice-front may have survived the rapid climatic amelioration (c. 13 ka BP) at the beginning of the Windermere Interstadial (marked by the Main Perth Shoreline) for perhaps a few decades.     

Late Devensian raised shorelines and ice limits in the inner Moray Firth area, northern Scotland

Marine, fluvial and fluvioglacial landforms and the deposits associated with them, have been mapped in the inner Moray Firth area. The landforms identified indicate a close association between the decay of the Late Devensian Scottish ice sheet and the formation of raised marine features. Analysis of the altitudes of the marine terraces has identified ten glacio-isostatically tilted raised shorelines of Late Devensian age, sloping down towards N25°E, at progressively lower gradients between 0.57 and 0.15 m/km. The shorelines were formed in close association with a westward- and southward-receding ice margin and the shoreline sequence suggests that rates of ice margin retreat were most rapid where the ice terminated in the sea.     

Stratigraphy and sedimentology of Devensian (Dimlington Stadial) glacial deposits,east Yorkshire,England

The stratigraphy and sedimentology of the glacial deposits exposed along the coast of east Yorkshire are reviewed. Critical sections at Filey Brigg, Barmston and Skipsea are examined to reassess the stratigraphy of Devensian Dimlington Stadial glacial deposits in the light of recent developments in glacial sedimentology. Sedimentary and glaciotectonic structures studied in the field and by using scanning electron microscopy are emphasised. Two hypotheses are considered for the genesis of the interbedded diamictons and stratified sediments. The first involves the deposition of lodgement till and/or deformation till followed by meltout till, which was overridden to produce more deformation till, reflecting periods of ice stagnation punctuated by glacier thickening. The second hypothesis, which is favoured on the basis of field evidence and micromorphology, involves the vertical accretion of a deforming till layer associated with cavity/channel or tunnel valley fills, beneath active ice. At Barmston the upper part of the diamicton contains elongate pendant structures containing gravels, indicating that the diamicton was saturated and able to flow. The diamictons, therefore, represent a complex sequence of tills deposited and deformed by active ice during the Dimlington Stadial. Previously published stratigraphical schemes involving classifications of multiple tills in east Yorkshire should be simplified and it is more appropriate to assign these to a single formation, the Skipsea Till Formation. Rhythmic glaciolacustrine and proglacial glaciofluvial sediments overlie the tills at Barmston and Skipsea. These were deposited in sag basins during deglaciation as the tills settled and deformed under thickening sediment and as buried ice melted out. Extensive sands and gravels cap the succession and were deposited on a sandur during the later stages of deglaciation.     

On the history of the Late Devensian Lake Sparks in southern Fenland,Cambridgeshire, England

A section in a gravel quarry at Somersham, Cambridgeshire, has revealed evidence for a lake, named Lake Sparks, in Fenland during the Late Devensian substage of the Pleistocene. Varved sediments were deposited in this lake over a minimum period of ca. 65 yr. The varved clays contain red diamicton clasts, interpreted as dump, delivered to the area by icebergs or floes from the ice-front in the Wash that deposited the Hunstanton Till. The lake is therefore considered a result of impounding by the Late Devensian ice advance on the east coast. A small number of pale varves have a characteristic structure indicating increased calcite deposition in the summer. They are interpreted as a result of cooler summers with reduced gelifluction from the surrounding Jurassic (Ampthill) Clay. Such gelifluction introduced a mudflow into the varved sequence at the southern end of the section. Pollen analysis confirms the derivation of the clays from the surrounding Ampthill Clay. The varved clays are succeeded by fluviatile sediments related to a delta building into the lake from the north. The delta sediments show periodic influx of sand into the lake interrupted by quiet periods with the development of Chara meadows. A thin spread of fluviatile gravels succeed the delta sediments, indicating the development of a braided river plain as the lake drained on the melting of the Late Devensian ice. This was followed by permafrost development, with the formation of thin thermal contraction cracks and coversand deposition. Later, degradation of the permafrost was associated with the formation of diapirs and a solifluction mantle, and incision of the fluviatile and lacustrine sediments took place. Flandrian peat and marl later filled the valley so formed. A radiocarbon date of 18310 yr BP from Salix leaves in a drift mud at the top of channel sands preceding lake sediment, in a neighbouring section, confirms the relation of the lake to the Late Devensian ice advance. The significance of the Late Devensian sediments at Somersham lies in the information they give on the timing and variety of processes related to drainage and ice movement in the period before, during and after the ice advance to the Wash. A period of low deposition rate in the lake was followed by rapid delta sedimentation and lake drainage, with implications for climatic change.     

An anisotropy of magnetic susceptibility (AMS) fabric record of till kinematics within a Late Weichselian low Baltic till,southern Sweden

Herein we report on the results of an anisotropy of magnetic susceptibility (AMS) fabric case‐study of two Late Weichselian tills exposed in a bedrock quarry in Dalby, Skåne, southern Sweden. The region possesses a complex glacial history, reflecting alternating and interacting advances of the main body of the Scandinavian Ice Sheet (SIS) and its ice lobes from the Baltic basin, perhaps driven by streaming ice. AMS till fabrics are robust indicators of ice‐flow history and till kinematics, and provide a unique tool to investigate till kinematics within and amongst till units. The till section investigated here contains ~8 m of the Dalby Till – a dark grey silt‐clay rich till deposited during one or more Baltic advance – overlain by ~1.5 m of the regional surface diamicton. AMS fabrics within the lower part of the Dalby Till conform to the regional surface fluting, and reflect sustained flow from the ENE with progressive increases in basal strain. A boulder‐rich horizon approximately 3 m from the base of the till marks a restricted excursion in till fabric direction, fabric strength and style of strain. Ice flow is from the SW and W in the upper section. We interpret these fabrics to record shifting ice flow and bed conditions at the margins of the Young Baltic Advance ice lobe in southern Sweden, prior to a short‐lived re‐advance of the main body of the SIS over mainland Sweden recorded by the surface diamicton.     

Depositional history of the Tyne valley associated with retreat and stagnation of Late Devensian Ice Streams

This paper provides sedimentological and morphological data from an investigation of the Late Devensian glacigenic deposits along the Tyne valley, northeast England. The area lies in the central sector of the British-Irish Ice Sheet, with the lowlands influenced by both the Tyne Gap and Tweed-Cheviot ice streams. The sequences here provide insights into the existence of complex, multi-phase activity within the British-Irish Ice Sheet. Field mapping of the area reveals kamiform topography in the Tyne lowlands and lower South Tyne valley, whilst the mid Tyne is characterised by high-level sandur terraces. Inset below the glacial features are river terraces. The sedimentary sequence comprises diamicton overlain by gravel and sandy gravels; sands, muddy sands and gravels; laminated silty sands and muds; and well sorted sands and gravel. The depositional environments indicate ice-contact, subaqueous and terrestrial sedimentation, with supraglacial, proglacial, subaquatic and paraglacial landsystems. Following the onset of deglaciation, westward retreat of Tyne Gap ice resulted in land to the east and southeast of its margin becoming ice-free. Continued/renewed southward flow of ice along the North Sea coast formed a persistent barrier to sediment-charged meltwaters draining the Tyne Gap ice margin. The separation of these two ice masses allowed a glacial lake to develop in the lower Tyne fed by a large proglacial sandur system, which with ice marginal retreat subsequently merged with Glacial Lake Wear. The sediment sequences record the final waning of the Tyne Gap ice stream, and are contiguous with sediments that extend west through the Tyne Gap and into the Cumbrian lowlands.     

The Dimlington Stadial/Dimlington Chronozone: a proposal for naming the main glacial episode of the Late Devensian in Britain

The term Dimlington Stadial is proposed as a climatostratigraphic name fer the main glacial episode of the Late Devensian in Britain, in preference to stratigraphically unsatisfactory terms, such as Late Devensian Glaciation (which includes the Windermere Interstadial and the Loch Lomond Stadial), icesheet glaciation or maximum of ice expansion, that are currently in use. The name is selected from a site on the East Yorkshire coast and refers to the interval between 26,000 and 13,000 radiocarbon years B.P. Dimlington Chronozone is the formal chronostratigraphic term for the equivalent period of time, and comprises the main part of the Late Devensian Sub-stage.     

A note on the glacial and late glacial history of caithness

It is generally accepted that in the last glaciation Scottish ice from the Moray Firth flowed to the northwest across Caithness depositing shelly drift. Examination of striae along the east coast of Caithness shows that some were formed by ice flowing into and not out of the Moray Firth. It is argued that the flow into the Moray Firth may have occurred in the last glaciation and that the shelly drift may be a relic of an earlier glaciation. The cliffs of Caithness were formed during the Loch Lomond Readvance and have since been raised isostatically and so have been protected from further marine erosion by their own wave-cut platform which can be traced into Orkney where it intersects the present level.     

Late Weichselian and Holocene seismostratigraphy and depositional history of the Gulf of Riga,NE Baltic Sea

The Lateglacial and postglacial sequence in the northern Gulf of Riga is sedimentologically subdivided into nine distinctive layers. In the seismo‐acoustic sequence these layers are correlated with seven seismic/acoustic units, which largely reflect different stages in the development of the Baltic Sea. A uniform layer of the Late Weichselian till, a layer of waterlain glacial diamicton (WGD), a varved succession of the Baltic Ice Lake, a brackish‐water/freshwater sandy/silty clay of Yoldia Sea, a FeS‐rich layer of Ancylus Lake and discordantly bedded sand of the Litorina Sea and present‐day gyttja are revealed both in sediment cores and in acoustic recordings. In general, the lateral extent of the distinguished sediment layers is gradually shrinking upwards in the Quaternary sequence towards the deepest, central depression of the gulf. Two distinguished regional discontinuities divide the Lateglacial and postglacial sediment sequence into three allounits: glacial diamicton deposits in the lower part; ice‐proximal WGD, glaciolacustrine and postglacial lake/marine deposits in the middle; and brackish‐water marine deposits in the uppermost part of the sequence. The presented detailed seismostratigraphic subdivision of the Quaternary sediment sequence of the Gulf of Riga permits a correlation/comparison with similar sequences across the Baltic Sea and in other former glaciated basins.     

Weichselian sediments at Foss‐Eikeland,Jæren (southwest Norway): sea‐level changes and glaciation history

The Jæren area in southwestern Norway has experienced great changes in sea‐levels and sedimentary environments during the Weichselian, and some of these changes are recorded at Foss‐Eikeland. Four diamictons interbedded with glaciomarine and glaciofluvial sediments are exposed in a large gravel pit situated above the post‐glacial marine limit. The interpretation of these sediments has implications for the history of both the inland ice and the Norwegian Channel Ice Stream. During a Middle Weichselian interstadial, a large glaciofluvial delta prograded into a shallow marine environment along the coast of Jæren. A minor glacial advance deposited a gravelly diamicton, and a glaciomarine diamicton was deposited during a following marine transgression. This subsequently was reworked by grounded ice, forming a well‐defined boulder pavement. The boulder pavement is followed by glaciomarine clay with a lower, laminated part and an upper part of sandy clay. The laminated clay probably was deposited under sea‐ice, whereas more open glaciomarine conditions prevailed during deposition of the upper part. The clay is intersected by clastic dykes protruding from the overlying, late Weichselian till. Preconsolidation values from the marine clay suggest an ice thickness of at least 500 m during the last glacial phase. The large variations in sea‐level probably are a combined effect of eustasy and glacio‐isostatic changes caused by an inland ice sheet and an ice stream in the Norwegian Channel. Copyright © 2002 John Wiley & Sons, Ltd.     

Constraining the chronology of Pleistocene glaciations on Svalbard: Kapp Ekholm re‐visited

The Kapp Ekholm site, in central Spitsbergen, shows alternating units of glaciomarine sandy silt and diamicton representing three glacial cycles and is key in reconstructing the Late Pleistocene glacial history of Svalbard. Part of the site is reinvestigated here by focusing on re‐dating two units (B and F) interpreted as interglacial/interstadial glaciomarine deposits, in order to constrain the controversial chronology. A combination of Optical Stimulated Luminescence (OSL) on quartz, infrared stimulated luminescence with a 50 °C readout temperature (IRSL₅₀) and post infrared‐infrared stimulated luminescence (pIR), both on feldspar, was applied. While Formation B was beyond the dateable range of OSL, IRSL₅₀ and pIR ages lead to the conclusion that this unit represents the Last Interglacial, Marine Isotope Stage (MIS) 5e, and the underlying diamicton the MIS 6 glacial. Formation F yielded ages implying that the formation represents the MIS 5a interstadial and the underlying diamicton is interpreted to represent the MIS 5b stadial. This agrees with conclusions drawn concerning the Pleistocene glaciations elsewhere on Svalbard.     

A major ice drainage pathway of the last British–Irish Ice Sheet: the Tyne Gap,northern England

The Tyne Gap is a wide pass, situated between the Scottish Southern Uplands and the English Pennines that connects western and eastern England. It was a major ice flow drainage pathway of the last British–Irish Ice Sheet. This study presents new glacial geomorphological and sedimentological data from the Tyne Gap region that has allowed detailed reconstructions of palaeo‐ice flow dynamics during the Late Devensian (Marine Isotope Stage 2). Mapped lineations reveal a complex palimpsest pattern which shows that ice flow was subject to multiple switches in direction. These are summarised into three major ice flow phases. Stage I was characterised by convergent Lake District and Scottish ice that flowed east through the Tyne Gap, as a topographically controlled ice stream. This ice stream was identified from glacial geomorphological evidence in the form of convergent bedforms, streamlined subglacial bedforms and evidence for deformable bed conditions; stage II involved northerly migration of the Solway Firth ice divide back into the Southern Uplands, causing the easterly flow of ice to be weakened, and resulting in southeasterly flow of ice down the North Tyne Valley; and stage III was characterised by strong drawdown of ice into the Irish Sea Ice Basin, thus starving the Tyne Gap of ice and causing progressive ice sheet retreat westwards back across the watershed, prior to ice stagnation. Copyright © 2009 John Wiley & Sons, Ltd.     

The origin and glaciodynamic significance of sandstone ridge networks from the Hirnantian glaciation of the Djado Basin (Niger)

The Djado Basin (Niger) was located beneath the inner part of the Late Ordovician ice sheet. The Felar‐Felar Formation consists mainly of glaciomarine deposits, associated with the major ice sheet recession within the glaciation, and is bounded by two glacial unconformities. Structures corresponding to sandstone ridges are found within the Felar‐Felar Formation. Sandstone ridges are several metres high, about 10 m wide and hundreds of metres long. These structures are organized in extensive anastomosed to sub‐polygonal networks. The association of sandstone ridge networks with the later glacial unconformity and with other glacial evidence suggests sub‐glacial conditions for their origin. Sandstone ridge sedimentological characteristics indicate that sandstone ridges result from the scouring of the Felar‐Felar Formation by sub‐glacial, turbulent and pressurized meltwater; then sub‐glacial cavities were infilled with sand derived from glacial abrasion. Sandstone ridge networks are comparable with tunnel channels and document unusual drainage structures of the inner part of the palaeo‐ice sheet.     

Reinterpreting Rotherslade,Gower Peninsula: implications for Last Glacial ice limits and Quaternary stratigraphy of the British Isles

Rotherslade on the Gower Peninsula in south Wales has been viewed as a key site for the reconstruction of Quaternary depositional environments in the British Isles. Since the early 20th century, and certainly since the 1980s, the accepted view has been that Rotherslade is the most westerly location on the south Gower coast where there is in situ basal till exposed and that, logically, this location marks the position of the LGM ice limit. However, reinvestigation of the sediments and their architecture, and analysis of clast fabrics and thin sections of critical sedimentary units, show that none of the exposed sediments has properties diagnostic of subglacial deposition or deformation. We postulate here that LGM ice terminated at the western side of Swansea Bay, a few kilometres to the north‐east of Rotherslade, and propose that the sedimentary sequence comprises Early to Middle Devensian periglacial sediments, overlain by a complex of Late Devensian, ice‐proximal outwash fan deposits, an assemblage of paraglacial debris and, finally, periglacial mass movement deposits. The proposed repositioning of the Late Devensian ice limit and the associated new subaerial interpretation of the sediments suggest that a reassessment of sedimentary sequences (Hunts Bay, Western Slade) and landforms (Paviland Moraine) farther west on Gower, which have attained similar stratigraphical status, is now warranted. Copyright © 2008 John Wiley & Sons, Ltd.     

Periglacial disruption and subsequent glacitectonic deformation of bedrock: an example from Anglesey,North Wales,UK

The deformed metasedimentary bedrock and overlying diamictons in western Anglesey, NW Wales, record evidence of glacier-permafrost interactions during the Late Devensian (Weichselian). The locally highly brecciated New Harbour Group bedrock is directly overlain by a bedrock-rich diamicton which preserves evidence of having undergone both periglacial (brecciation, hydrofracturing) and glacitectonic deformation (thrusting, folding), and is therefore interpreted as periglacial head deposit. The diamicton locally posses a well-developed clast macrofabric which preserves the orientation of the pre-existing tectonic structures within underlying metasedimentary rocks. Both the diamicton and New Harbour Group were variably reworked during the deposition of the later Irish Sea diamicton, resulting in the detachment of bedrock rafts and formation of a pervasively deformed glacitectonite. These structural and stratigraphic relationships are used to demonstrate that a potentially extensive layer of permafrost developed across the island before it was overridden by the Irish Sea Ice Stream. These findings have important implications for the glacial history of Anglesey, indicating that the island remained relatively ice-free prior to its inundation by ice flowing southwards down the Irish Sea Basin. Palynological data obtained from the diamictons across Anglesey clearly demonstrates that they have an Irish Sea provenance. Importantly no Lower Palaeozoic palynomorphs were identified, indicating that it is unlikely that Anglesey was overridden by ice emanating from the Snowdon ice cap developed on the adjacent Welsh mainland. Permafrost was once again re-established across Anglesey after the Irish Sea Ice Stream had retreated, resulting in the formation of involutions which deform both the lower bedrock-rich and overlying Irish Sea diamictons.     

A revised seismic stratigraphy for Quaternary deposits on the inner continental shelf west of Scotland between 55°30'N and 57°30'N

A stratigraphy for Quaternary deposits on the western Scottish shelf has been erected using seismic and borehole data. Eight new formations are defined and described with evidence presented for the environ-ment of deposition of each formation. Most of the Quaternary sediments preserved on the shelf arc shown to have accumulated under stadial or glacial conditions. The possible age of each formation is discussed within the context of evidence provided from the mainland, shelf and deep-sea cores. Two are thought to be pre-Devensian, one is possibly pre-Devcnsian. one is possibly Early and/or Middle Devensian, two are probably Late Devensian, one is Late Devensian to Holocenc and one Present day in age. It is suggested that the Late Devensian ice reached the shelf margin south of the Outer Hebridcan Platform.